In a principal aspect the present invention relates to a kit comprised of tools to effect removal of broken spark plugs from a cylinder head.
Motor vehicle internal combustion engines include spark plugs threaded into the cylinder head so as to provide an electric ignition spark to ignite combustible gasses within each cylinder. Each spark plug has an outer contact connected to a current source. The outer contact connects to a conductor leading to a spark gap at the tip of the plug. Thus ignition is effected by means of a spark in the gap at the tip which projects through the cylinder head into the cylinder.
Spark plugs utilized for such ignition have a variety of constructions. Typically, a spark plug will include an axial conductor encased in a porcelain insulator, an outer end contact terminal and a threaded cylindrical body which encases the parts of the spark plug and enables threaded insertion and removal of the plug from a threaded bore in the cylinder head.
Recently, at least one vehicle manufacturer has adopted a spark plug construction which is somewhat difficult to remove from the cylinder head and which on occasion will break during removal. Thus, the problem of removal and replacement of spark plugs from the cylinder head is exacerbated by the design of the plug and the manner in which the plug is inserted into the cylinder head. This issue is especially prevalent in certain Ford Motor Company vehicles and is described in a Technical Service Bulletin #TSB 06-15-2 of the Ford Motor Company. That Technical Service Bulletin is incorporated herewith by reference inasmuch as it defines a problem associated with spark plug replacement and also suggests a solution to effect removal of spark plugs, and, in particular, broken spark plugs from the cylinder head of a motor vehicle engine.
Specifically, during attempted removal of a plug, the cylindrical spark plug tip may break and separate from the body of the threaded plug. As such, the tip remains positioned within the cylinder head and must be removed before a new plug can be threaded into the cylinder head. Such removal is exceedingly difficult. A tool which has been used to effect removal of the broken tip forms threads or is tapped into the tip. The tool is thus screwed into the plug tip and the threading tool and attached tip are then pulled from the cylinder head. While this approach is useful, it is exceedingly time consuming, and, moreover, aligning the tool and effecting a successful threading operation is difficult. Finally, a porcelain sleeve retained within the tip may preclude appropriate retrieval of the spark plug tip. Thus, there has developed a need to provide a tool or a set of tools which will address the various issues associated with the removal of a broken spark plug from the cylinder head of a motor vehicle, and, in particular, from the cylinder head of vehicles of the type described in the Technical Service Bulletin referenced above.